I think, most of all, you should dig through LWN and the kernel documentation. Both are great learning resources. LWN has many introductory/educational articles

I think, most of all, you should dig through LWN and the kernel documentation. Both are great learning resources. LWN has many introductory/educational articles about the very topics you care about. (Also, Jens Axboe wrote a long and great explanation why blk-mq was necessary, which you should seek out. He did the same for io_uring) I highly recommend Gregg's Systems Performance (2nd edition came out in 2020). While the book is focused on performance rather than development, Gregg does a great job explaining a huge number of concepts without going too deep, specifically related to memory, fs, and block I/O. Unfortunately, in terms of many of the things you care about, books tend to be outdated. Kerrisk's Linux Programming Interface is over 10 years old, and covers only ext2. Robert Love's great books on the kernel are hugely useful (though less intended for application developers) but also slightly outdated.